Cabin altitude and oxygen use indicator



' June 21,1949.

N. F. HOSFORD 2,473,586

CABIN ALTITUDE AND OXYGEN USE INDICATOR Filed April 13, 1948 36 as u [Ill ////77/ IN VEN TOR.

Ivan/7m E HUEFUHD BY 24 HTTOQ y Patented June 21 1949 UNITED STATES; PATENT OFFICE CABIN ALTITUDE ANDQOXYGEN USE V INDICATOR 1 Application April 13, is ia scri al No. 20, 783

10 Claims. (c1.177- 3i1) r l 2 This invention relates to an altitude indicator, [3 in the rear thereof. The front of the casing is and more particularly to-a cabin altitude and oxyclosed by means of a bezel ring it and a cover gen use indicator for aircraft. glass l4 through which a dial l5 and a cooperat- It is an object of my invention to provide an ing pointer lfi may be viewed. For purposes hereindicator or warning unit to indicate the need for 5 inafter appearing, the dial I5 is provided with a oxygen in a high flying aircraft when theambient small aperture -ll' in the lower portion thereof. pressure of the cabin falls to a predetermined The pointer I6 is fixed to a shaft lta journalled level. a a through the center of the dial 15.,- A. pinion [8 Another object of my present invention is to prois fixed to the rear end of the shaft Mia and is vide an indicator of the character indicated in 10 adapted to be rotated by a sector gear lQmeshing which the warning or signal given at the pretherewith. The sector gear l9 isfixedto the end determined altitude is extinguished upon supplyof a horizontal shaft suitably journalled'within ing the required oxygen to the aircraft cabin. the casing ll. Fixed to the other end of the shaft Still another object of this invention is to pro- '21! is a collar 2| provided with a radially extendvide an indicator-of the character indicated in 15 ing arm 22. Pivotedto the end of said arm is a which the Warning or signal is again given upon 111114 23 interconnecting an arm 24 fixed in a stud a decrease in cabin pressure below a second p-re- 25 of an aneroid 2E. determin d level, g c The aperture l2 provided in the casing ll will Yet another object of my invention is to provide pe m t he ambient pressure of the instrument to an indicator of the general character described in 20 afiect the aneroid 26. The expan n -v which the warning or signal indication is opera traction of the aneroid due to the varying ambient tive by the cabin pressure and made inoperative pressure will shift the link 23 to rotate the shaft upon the operation of an oxygen regulator nor- 2|] y y I" t e The rotation of the mally forming a part of the equipment carried by shaft 20 will in turn cause a rotation of the pin-- high flying ir raft nd/ personneL 5 ion l8, thereby moving the pointer 56 over the dial A further object of this invention is to provide l5 0f the instrument- A reading Of e P 61 an indicator of the general character described in and l Will h give an indication of the a iwhich the failure of the oxygen regulator equip- 8111? Pressure affecting t e instrument in terms ment between prescribed pressure limits is indiof alti ude. This ambient pressure y be e her cated by my instrument, v barometric pressure or it may be the pressure Still a further object of my invention is to Within a s a ed Cabin of an aircraft. provide an indicator of the general character Means is how P de o i d cate the ambient described which shall consist of few and simple PI Q at Which o ygen is requ by the pilot, parts, relatively inexpensive to manufacture, /01 p en e p s being q e t which shall be positive and accurate in its operato that found at an altitudeof 10,000, feetx a tion, andyet be practical and eflicient to a high o this end there is p oy d d a electrical la p degree i use I I g I socket Z'l suitably mounted within the instrument Other objects of this invention will in part be casing NV a d directly be d; the apert e-'1 obvious and in part hereinafter pointed out. provided in the dial IS. A small electrical light In the accompanying drawings forming a, part, 40 lamp Z8 is provided for the 800181817 21, and may. of this specificatign in which one of the various extend slightly beyOl'ld the (118115. One terminal possible illustrative embodiments of this inven- 0 e amp socket 21 is grounded as, at 29, whil tion is shown, and wherein similar reference charo r terminal. is connected y a. w e 0 acters designate corresponding parts throughout ou h t aperture in reality 9; Socket and the t iews, plug connector, tothe negative side of a battery Fig. l-is a front elevational view of an instru 3L The positive ide-0f t a ery 1 m t incorporating my invention, whil nectedvia leads 32 and 33 to-oneterminal of a ,Fig. 2 is a perspective view taken approximately thermal responsive sw ch 34. I along the, line 22 of Fig. 1,. portions thereof The thermal switch 34 comprises two switch being shown in cross-section; the parts thereof arms 35. and 36 provided with sui a e end 00nbeing shown electrically connected to form a schetacts normally closed. I'Ihe switch. arm 35 is fur matic wiring diagram. ther provided with aheater strip in intimate.

In the drawings, the numeral ill designates contact therewithj The twocontact arms are an instrument embodying my invention, enclosed. inclosed no glass'envelope38 suitably vmounted n a casing H provided with two openings l2 and. 5 5,W ithin thef'jcasing ll. 'i I nova eceosciu 5;; v as: in)

placed from one the other by anamount equivalent to the dilferent pressures set into the instrument. Both arms, however, are adapted upon rotation of the shaft 20 a suitable degree, to engage the conducting insert 4| sequentially and then concurrently. In the description to be hereinafter made, the contact arm 43 will be referred to as the low altitude contact, while the contact arm 44 will be referred to as the high altitude contact.

The low altitude contact 43 is grounded as indicated at 45. When the contact arm 43 engages the conducting insert 4| of the block 42, a circuit will be completed for the electric light 28 to provide a visual indication that a particular ambient pressure exists. The engagement of the of oxygen through an oxygen regulator such as shown in the copending applications of B. B. Holmes bearing Serial No. 482,016 and Serial No. 569,777 filed, respectively,on April 6, 1943 and December 26, 1944 will operate a blinker signal.

A switch 48 of a blinker signal 50 is operated by the movement of the diaphragm therein as the oxygen passes through the'supply line 52 of the oxygen regulator (not shown). The operation of the blinker switch provides an electric circuit for the heater element 31 on the switch arm 36. This circuit maybe traced from the negative side of the battery 3| through the blinker switch contacts and a lead 49 connected to the heater element 31, then by way of switch arm'36 and leads 33, 32 to the positive side of the battery 3|.

The heater element 31 will become heated and due to its intimate co-ntactwith the switch arm 36, will flex the switch arm to an open position. The opening of the switch 35, will open the energizing circuit for the lamp 28.

So long as the blinker switch 48 is operated by the flow of oxygen through the regulator, the heater element 31 will be intermittently connected into the circuit described to maintain the switch arm 35 and 3G in an open position. Should the regulator fail for any reason, a twenty or thirty second delay will permit the heater element to cool sufliciently to permit the switch 35, 36 to close again to complete the energizing circuit described for the lamp.

Means is now provided to indicate a second ambient pressure at which the oxygen supply is insulficient to maintain comfortable flight in view of the further decrease in the ambient pressure, the second predetermined pressure be:- ing equivalent to an altitude of $0,800 feet.

"To this end, the high altitude switch contact 46 is provided. The contact 44 is connected by a lead 50 to the positive terminal lead 32. When the second pressure condition is attained, the contact 44 will engage the conducting insert 4| of the block 42. The low altitude contact 43 also engages the insert 4|. Despite the open conditions of the switch 35, 36 due to the operation of the blinkerswitch 48, the engagement of the contact 44 with the insert 4| will ground the positive side of the battery 3| through the grounded contact 43 to complete a second energizing circuit for the lamp 28.

There is thus provided by my invention a pres- .sure indicator in which a signal will be given when a proscribed ambient pressure exists where oxygen is required for safe air travel, the signal being extinguished upon operation of an oxygen regulator. A second indication is also provided by my instrument to indicate a pressure at which the oxygen. supplied is insufficient for maintaining safe flight at that pressure.

As various possible embodiments may be made in the above invention, and as various changes may be made in the embodiment above set forth, it is to be understood that all matter herein described or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. An oxygen requirement indicator for use with an oxygen regulator, comprising a pressure responsive member subjected to the ambient pressure of an aircraft cabin, a dial, a pointer cooperating with said dial and driven by said member to indicate the cabin pressure, a switch operable by said member when the cabin pressure reaches apredetermined value, a warning signal operable upon operation of said switch, and means associated with the oxygen regulator to extinguish said signal when oxygen flows through the regulator.

2. An oxygen requirement indicator for use with an oxygen regulator, comprising a pressure responsive member subjected to the ambient pressure of an aircraft cabin, a dial, a pointer cooperating with said dial and driven by said member to indicate cabin pressure, a switch operable by said member when the cabin pressure reaches a predetermined value, a warning signal operable upon operation of said switch, a blinker switch intermittently operable by the flow of oxygen throughthe regulator to extinguish said signal, and a second switch operable at a lower predetermined pressure by said member to operate said warning signal despite the operation of said blinker switch.

3. An oxygen requirement indicator for use with an oxygen regulator, comprising an aneroid subjected to the ambient pressure of an aircraft cabin, a dial, a pointer cooperating with said dial and driven by said aneroid to indicate cabin pressure, a switch operable by said aneroid when the cabin pressure reaches a predetermined value, a warning signal operable upon operation of said switch, a blinlzer switch intermittently operable by the flow of oxygen through the regulator, and a time delay switch operable by the operation of said blinker switch to extinguish said signal.

4. An oxygen requirement indicator for use with an oxygen regulator, comprising an aneroid subjected to the ambient pressure of an aircraft cabin, a dial, a pointer cooperatin with said dial and driven by said aneroid to indicate cabin pressure, a switch operable by said aneroid when the cabin pressure reaches a predetermined value, a warning signal operable upon operation of said switch, a blinker switch intermittently operable by the fiow of oxygen through the regulator, a time delay switch operable by the operation of said blinker switch to extinguish said signal, and a second switch operable by said aneroid at a lower predetermined pressure to operate said signal despite the operation of said time delay switch.

5. An oxygen requirement indicator for use with an oxygen regulator, comprising an aneroid subjected to the ambient pressure of an aircraft cabin, a dial, a pointer cooperating with said dial and driven by said aneroid to indicate cabin pressure, a switch operable by said aneroid when the cabin pressure reaches and falls below a predetermined pressure, a warning signal operable by said switch upon operation thereof, a blinker switch intermittently operable by the flow of oxygen through the regulator, and thermal switch means operative by the operation of said blinker switch to extinguish said signal, said thermal switch becoming inoperative upon failure of the blinker switch to permit operation of the signal by said first switch when the cabin pressure is below the predetermined pressure.

6. An oxygen requirement indicator for use with an oxygen regulator, comprising an aneroid subjected to the ambient pressure of an aircraft cabin, a dial, a pointer cooperating with said dial and driven by said aneroid to indicate cabin pressure, a switch operable by said aneroid when the cabin pressure reaches and falls below a predetermined pressure, a warning signal operable by said switch upon operation thereof, a blinker switch intermittently operable by the flow of oxygen through the regulator, thermal switch means operative by the operation of said blinker switch to extinguish said signal, said thermal switch becoming inoperative upon failure of the blinker switch to permit operation of the signal by said first switch when the cabin pressure is below the predetermined pressure, and a second switch operable by said aneroid at a lower predetermined pressure to operate said signal despite the operation of said blinker switch.

7. An oxygen requirement indicator for use with an oxygen regulator, comprising a pressure responsive member subjected to the ambient pressure of an aircraft cabin, a switch operable by said member when the cabin pressure reaches a predetermined value, a warnin signal operable upon operation of said switch, a blinker switch intermittently operable by the flow of oxygen through the regulator to extinguish said signal, and a second switch operable at a lower predetermined pressure by said member to operate said warning signal despite the operation of said blinker switch.

8. An oxygen requirement indicator for use with an oxygen regulator, comprising an aneroid subjected to the ambient pressure of an aircraft cabin, a switch operable by said aneroid when the cabin pressure reaches and falls below a predetermined pressure, a warning signal operable by said switch upon operation thereof, a blinker switch intermittently operable by the flow of oxygen through the regulator, thermal switch means operative by the operation of said blinker switch to extinguish said signal, said thermal switch becomin inoperative upon failure of the blinker switch to permit operation of the signal by said first switch when the cabin pressure is below the predetermined pressure, and a second switch operable by said aneroid at a lower predetermined pressure to operate said signal despite the operation of said blinker switch.

9. An oxygen requirement indicator for use with an oxygen regulator, comprising a pressure responsive member subjected to the ambient pressure of an aircraft cabin, indicating means driven by said member to indicate the cabin pressure, a switch operable by said member when the cabin pressure reaches a predetermined value, a warning signal operable upon operation of said switch, and means associated with the oxygen regulator to extinguish said signal when oxygen flows through the regulator.

10. An oxygen requirement indicator for use with an oxygen regulator, comprising an aneroid subjected to the ambient pressure of an aircraft cabin, indicating means driven by said aneroid to show cabin pressure, a switch operable by said aneroid when the cabin pressure reaches a predetermined value, a warning signal operable upon operation of said switch, a blinker switch intermittently operable by the flow of oxygen through the regulator, and a time delay switch operable by the operation of said blinker switch to extinguish said signal.

NORMAN F. HOSFORD.

file of this patent:

UNITED STATES PATENTS Name Date Lindsay Jan. 27, 1948 Number 

